Electrodynamic linear motor

ABSTRACT

A synchronous electrodynamic motor comprises a primary part with a yoke which has lateral parts. The lamination stacks of the primary part carry a multiphase AC winding and are subdivided in height into portions which are surrounded by respective direct current excitation windings whose magnetic flux path is closed only through the lateral parts of the yoke.

United States Patent Leitgeb [54] ELECTRODYNAMIC LINEAR MOTOR Inventor:Wilhelm Leitgeb, Berlin, Germany Siemens Aktiengesellschaft, Berlin,Munich, Gennany Aug. 2, 1971 Assignee:

Filed:

Appl. No.:

[30] Foreign Application Priority Data Aug. 12, 1970 Germany ..P 20 40986.3

U.S. CI ..3l0/l2, 310/27 Int. Cl. ..H02k 41/02 Field of Search ..310/12-14;

318/135,121;104/148,l48 LM References Cited UNITED STATES PATENTSRosenberg et a1. ..3l0/13 [451 Oct. 17, 1972 3,456,136 7/1969 Pietro..3l0/12 3,575,650 4/1971 Fengler ..3l8ll35 3,577,929 5/1971 Onoda etal. ..l04/l48 LM 3,594,622 7/1971 lnagaki "318/135 Primary Examiner-D.F. Duggan Attorney-Curt M. Avery et a1.

[57] ABSTRACT A synchronous electrodynamic motor comprises a primarypart with a yoke which has lateral parts. The lamination stacks of theprimary part carry a multiphase AC winding and are subdivided in heightinto portions which are surrounded by respective direct currentexcitation windings whose magnetic flux path is closed only through thelateral parts of the yoke.

5 Claims, 4 Drawing Figures ELECTRODYNAMIC LINEAR MOTOR The inventionrelates to an electric motor and more particularly to a synchronouselectrodynamic linear motor.

Electrodynamic linear motors may be designed as synchronous orasynchronous machines. In a synchronous motor of this type, the fieldexcitation is provided by a special excitation winding which ispreferably energized by direct current.

In a preferred embodiment of such a machine, the direct currentexcitation winding is mounted on the inductor or primary part inaddition to the multiphase AC winding which produces the travellingfield. The secondary part of the linear motor has alternately positionedmagnetic .and non-magnetic sectors corresponding in length to the poledivision of the multiphase AC winding of the inductor or primary part.Such an arrangement has the advantage that the secondary part'of .thelinear motor is free of windings. The excitation winding is mounted onthe inductor in such a way that a magnetic flux is induced transverse tothe area of the air gap.

My invention is an improvement of a synchronous electrodynamic linearmotor of the aforedescribed type.

It is an object of the invention to provide a synchronous electrodynamiclinear motor in elec-- directions to produce two opposite magneticattractions which substantially cancel each other.

A further object of the invention conjoint with those aforementioned isto provide a synchronous electrodynamic linear motor which functionswith efficiency, effectiveness and reliability and produces a hightorque.

In accordance with the invention, the inductor comprises laminationstacks on which the multiphase AC winding is mounted. The height of thelamination stacks is subdivided; each portion being enclosed by anexcitation winding through which direct current flows in a mannerwhereby magnetic flux closes only through the lateral parts of the yoke.As a result, the total magnetic flux produced by the excitation windingis guided in different directions across the air gap of the electrodynamic motor in a manner whereby the middle part of the yokeconnecting the lamination stacks is free from the return flow oftheflux.

In order that this type of linear motor with subdivided laminationstacks may function properly, it is necessary to arrange the conductorsor turns of the AC winding which produces the travelling field in theindividual parts of the lamination stack, which are displaced by onepole division. Since this requires a somewhat more complicated windingdesign, it is recommended that rather than subdivide the conductors ofthe multi-phase AC winding, the magnetic sectors in the secondary partof the linear motor be subdi- 2 vided with respect to their height, intocomponent sections corresponding to the lamination sections, and thatthe component sections be mutually displaced by one pole division. Thisarrangement has the further advantage that the magnetic flux whichcrosses the air gap in two directions produces two opposite magneticattractions which cancel each other during a unilateral change in airgap.

, netic flux. The middle part of the yoke is used for fastening theparts of the lamination stack.

It is expedient to interconnect the magnetic sectors of the secondarypart of the motor by non-magnetic material The magnetic sectors of thesecondary part may be embedded, for example, in one or more componentsof concrete.

In order that the invention may be readily carried into effect, it willnow be described with reference to the accompanying drawings, wherein:

FIG. 1 is a view, partly in section, of an embodiment of theelectrodynamic linear motor of the invention;

FIG. 2 is a schematic diagram of the secondary part of the motor of theembodiment of FIG. 1;

FIG. 3 is a view, partly in section, of another embodiment of theelectrodynamic linear motor of the invention; and

FIG. 4 is a schematic diagram of the secondary part of the motor of theembodiment of FIG. 3.

In the FIGS, the same components are identified by the same referencenumerals.

In the embodiment of FIG. 1, an electric linear motor 1 comprises twoadjacent motors. The inductor or primary part of the motor comprises acommon yoke2 and lamination stacks positioned between lateral legs 3 and3 of the yoke. The lamination stacks are divided in height into twoequal parts 4a and 4b, 4a and 4b, and 4a" and 4b", and are enclosed byexcitation windings 5a and 5b, Sal and SM, 5a2 and 5b2, and 5a and 5b",which, as previously mentioned, are traversed by direct current.

The stack portions 4a and 4b, and so on, expose two air gaps 6 and 6'whose side flanks contain, in open grooves, the conductors or turns ofmultiphase AC windings 7, 7a, 7b and 7". The laminated stack portions 40and 4b, situated between the air gaps 6 and 6', are interconnected by acomponent 8 of non-magnetic material and another component 9 ofnon-magnetic material, and are affixed to the center part of the yoke 2.

The electrodynamic linear motor 1 of the invention has a secondary part10 (FIG. 2), which is devoid of windings and comprises magnetic andnon-magnetic sectors which extend into'the air gaps 6 and 6'. Thelengths of the magnetic and non-magnetic sectors of the secondary part10 correspond to the pole division T of the multiphase AC windings 7,and so on. The

magnetic sectors of the secondary part 10 comprise iron components 11a,11b, 11a, 11b, 11a", having heights corresponding to the heights of thestack portions 4a and 4b, 4a and 4b and 4a" and 4b". The iron components11a, 11a and 11a", which correspond in height to the lower stack oflaminations, are mutually displaced relative to the iron components 11b,11b and 11b", which correspond in height to the upper stack oflaminations, by a pole division T in the longitudinal direction of theair gaps 6 and 6.

The iron components 11a, and so on, are affixed to a stationary concretecomponent 13 which connects the secondary parts 10 of both motors vianon-magnetic members 12a, 12a and 12a. The iron components 11b, and soon, are affixed to the concrete component 13 via non-magnetic members12b, 12b and 12b". The displaced arrangement of the magnetic sectors ofthe secondary part 10 provided for the individual parts of thelamination stack permits the multiphase AC windings 7, and so on, tocomprise winding rods arranged in a continuous groove in both laminatedportions 4a and 4b, and so on.

The magnetic flux curve is shown in broken lines in FIG. 1 and isproduced in the inductor of the linear motor 1, by the excitationwinding through which direct current flows. It may be assumed that themagnetic flux in the air gaps 6 and 6' is virtually present only inthese regions where the predominant portion of the space between thelamination stacks 4a and 4b, and so on, is bridged by the ironcomponents 11a and 11b, and so on, of the secondary part 10. Forces aretherefore exerted against the movable inductor which produce a relativemovement between the movable inductor and the stationary secondary part10. These forces are in proportion to the air gap surface of theinductor, to the air gap induction and the magnetic lines of force ofthe multiphase AC windings 7, and so on.

FIGS. 3 and 4 show another embodiment of the invention wherein thelinear motor 1 comprises two adjacent motors and contains stacks oflaminations whose height is divided into three stack parts 4a, 4b and4c, and so on, each stack part being enclosed by an annular excitationwinding 5a, 5b and 5c, and so on.

In the embodiment of FIG. 3, the conductors of the multiphase ACwindings 7, 7a, 7b and 7 of all the lamination stacks 4a, 4b and 4c, andso on, are arranged in a continuous groove. The magnetic sectors of thesecondary part 10 of the motor (as illustrated in FIG. 4) arerespectively subdivided into iron components 11a, 11b and 11c, and soon, whose heights correspond to the respective parts of the laminationstacks 4a, 4b and 4c, and so on. The respective components are mutuallydisplaced by one pole division T,.

The magnetic flux 0 in the components has a curve, shown in broken linesin FIG. 3, which runs in one direction toward said components andterminates in said components in the other direction. The flow directionof the direct currents in the excitation windings 5a, 5b and 5c, and soon, is so selected that the produced magnetic flux 0 closes only throughthe lateral legs 3 of the yoke 2.

While the invention has been described by means of specific examples andin specific embodiments, I do not wish to be limited thereto, forobvious modifications will occur to those skilled in the art withoutdeparting from the spirit and scope of the invention.

I claim:

1. An electrodynamic linear motor comprising a primary part having ayoke with lateral parts, a plurality of direct current excitationWII'ldlIIgS mounted on said primary part, a multiphase AC windingmounted on the primary part for producing a travelling field, asecondary part having a plurality of alternating magnetic andnon-magnetic sectors whose lengths correspond to a pole division of themultiphase AC winding, said primary part comprising stacks oflaminations subdivided in height into a plurality of component sectionswhich are surrounded by said respective direct current excitationwindings, the magnetic flux path of the direct current excitation beingclosed only through said lateral parts of said yoke of the primary part.

2. An electrodynamic linear motor as claimed in claim 1, wherein themagnetic sectors of the secondary part of the motor are subdivided inheight into component sections corresponding to the stacks oflaminations, and the component sections are mutually displaced by onepole division of the AC winding.

3. An electrodynamic linear motor as claimed in claim 1, wherein the ACwinding has a plurality of conductors arranged in individual stacks oflaminations displaced by a pole division of the AC winding.

4. An electrodynamic linear motor as claimed in claim 1, comprising aplurality of component synchronous electrodynamic linear motorspositioned adjacent each other and having their primary parts joined bya common yoke.

5. An electrodynamic linear motor as claimed in claim 2, furthercomprising non-magnetic material interconnecting several componentsections of the magnetic sectors of the secondary part.

1. An electrodynamic linear motor comprising a primary part having ayoke with lateral parts, a plurality of direct current excitationwindings mounted on said primary part, a multiphase AC winding mountedon the primary part for producing a travelling field, a secondary parthaving a plurality of alternating magnetic and non-magnetic sectorswhose lengths correspond to a pole division of the multiphase ACwinding, said primary part comprising stacks of laminations subdividedin height into a plurality of component sections which are surrounded bysaid respective direct current excitation windings, the magnetic fluxpath of the direct current excitation being closed only through saidlateral parts of said yoke of the primary part.
 2. An electrodynamiclinear motor as claimed in claim 1, wherein the magnetic sectors of Thesecondary part of the motor are subdivided in height into componentsections corresponding to the stacks of laminations, and the componentsections are mutually displaced by one pole division of the AC winding.3. An electrodynamic linear motor as claimed in claim 1, wherein the ACwinding has a plurality of conductors arranged in individual stacks oflaminations displaced by a pole division of the AC winding.
 4. Anelectrodynamic linear motor as claimed in claim 1, comprising aplurality of component synchronous electrodynamic linear motorspositioned adjacent each other and having their primary parts joined bya common yoke.
 5. An electrodynamic linear motor as claimed in claim 2,further comprising non-magnetic material interconnecting severalcomponent sections of the magnetic sectors of the secondary part.